The present invention relates to a self-rescue apparatus for automobiles and more particularly pertains to an auto creeper tread used for automobile self-rescue.
At present, automobiles usually get stuck or trapped in the following terrains: deserts, swamps, muddy roads and snow. Automobiles usually skid or sink into the ground when they get stuck. In situations when automobiles get stuck into the ground and cannot make an escape, drivers could only seek help from other automobiles to give it a tow. Sometimes, if the incident occurs in a remote area far away from people or towns, drivers would be susceptible to intolerable distress, delay in schedule and disturbance in work. It is most common to make an escape by means of tow truck. Towing is advantageous in that it is simple and easy to perform as it only requires one other automobile and a trailer rope. To prevent an automobile from getting stuck, a metal chain in the form of continuous enclosed rings can be mounted onto the surface of an automobile tire to form an anti-skid chain so as to increase the adhesive force of the tire towards the ground. It is one of the most effective measures to prevent an automobile from skidding on plain snowy roads and muddy roads. It is deficient in that it is useless if the automobile sinks into a deeper pit or if any of the tires loses contact with the ground.
Self-rescuing apparatus for automobiles generally includes winches, differential locks and antiskid plate.
1. Winches
The operating principle of a winch is to use a generator or a PTO power output to drive a gear cluster to reel a steel cable in order to tow the automobile out. The largest traction generated by a winch is 9,500-12,000 pounds, which is two to four times the weight of a common automobile. A winch costs about RMB 5,000 to RMB 20,000. The advantage of a winch is that it has a large torque and a high successful rate. Its disadvantage is that it must have an anchor point. In other words, there must be another vehicle, a tree or other fixed objects within a distance of 30 to 50 meters for the winch hook to hook onto, and the anchor point must be right in front of the automobile. Anchor points could also be constructed by integral ground anchors or tires buried deep into the ground. However, it requires much effort and is easily susceptible to failure due to the soft soil texture at the position of the anchor point. Moreover, a large number of accessories such as tree strap, pulley assembly, U-shaped hook and leather gloves are required when using a winch. Users are also required to master certain skills.
An electric winch can only continuously operate for several minutes. Therefore, it is necessary to reduce as much as possible the rotating time of a winch, or the generator would be damaged due to overheating or the accumulator cell would be subjected to over discharge. A winch is usually installed in the middle of a bumper in front of the head of an automobile. As a winch weighs 30 kilograms, the head of the automobile would sink downward. It is therefore necessary to improve shock absorption. If an automobile has to be towed from its back occasionally, another winch has to be installed at the tail of the automobile. Another disadvantage is that a sufficient safe space in front of or behind the automobile to be rescued is required for placing an anchor point. However, there is no guarantee to have such a large empty area at places where automobiles easily get stuck.
2. Differential Lock
The operating principle of a differential lock is to lock the differential so that power could be evenly applied to each tire, thereby preventing all power from being applied to the spinning tire as the other tire loses contact with the ground. It is advantageous in that it can be operated without the need of any person getting out of the automobile, and that it performs well on wet and slippery roads. Differential lock is deficient in that it can only be used on wet and slippery roads. When the automobile gets on dry and firm roads, it is necessary to disengage the differential lock immediately, or the gears would be damaged. Moreover, when the tires of the automobile lose contact with the ground and the chassis of the automobile is lifted, a differential lock could not help much with the rescue.
A set of differential locks costs about RMB 10,000 to RMB 20,000 in general. Only a minority of luxurious four-wheel drive automobiles are equipped with differential locks. Currently, the majority of automobiles are not designed for the installation of differential locks. Therefore, differential locks are not common rescuing tools.
3. Antiskid Plate
An antiskid plate is formed by processing metal boards or hard plastic boards having mesh openings or screw lines. By placing an antiskid plate between the ground and the tires, friction is increased and the automobile could be pulled out of the area where it gets stuck. It is advantageous in that it is effective if the ground is firm and the automobile is not sinking deep into the ground. It is also convenient to carry and simple to use. Its disadvantage is that it becomes useless when the automobile sinks deep into the ground, especially when the chassis of the automobile is being lifted and thereby causing the tires to lose contact with the ground.
There are also some patented inventions which utilize the principle of antiskid plates by installing larger accessories on an antiskid plate to generate more friction. These inventions appear to be feasible theoretically. However, when an automobile sinks deeper into the ground, especially when the chassis of the automobile is being lifted and thereby causing the tires to lose contact with the ground, the friction generated between the antiskid plate and the tires is far from being able to overcome the resistance generated by the adhesion of the automobile towards the slough, snow and sand. Such resistance is usually equal to or greater than the weight of an automobile. Depending on the ratio between the depth of the sinkage and the surface area of the ground, the resistance varies from several hundred kilograms to several tons or more. There was once an automobile which is towed by an industrial hoister after it sinks into a sandy ground and fails to be rescued by a winch offered by another vehicle. The automobile was unable to be retrieved despite that the casing and the chassis thereof are substantially detached from each other. It is even impossible for relevant anti-sink devices derived from antiskid plate to generate sufficient traction to get the automobile out of the area where it gets stuck.